Vacuum packaging of products generally requires a semi-packaged product to be subjected to a controlled environment (e.g., inert gas, pressure, temperature, etc.) within a chamber of some kind, in order to vacuumize and seal the product. During the packaging process, the products first have to be processed and pre-packaged, for example, by inserting the product into an open bag made from a suitable material. Subsequently, the products are moved towards a vacuumization and sealing station, where vacuumization and sealing takes place. In order to provide the controlled environment, semi-packaged products usually have to be moved into a chamber, which is then closed in order to establish the controlled environment. After vacuumization and sealing, the products have to be removed from the chamber, which has to be opened for this step. Packaging apparatuses can comprise a number of components that enable to moving of products and of components of the packaging apparatus with respect to each other. For example, a packaging apparatus can comprise electric or hydraulic actuators that open and close the chamber and/or drive a conveyor belt.
EP0381020 discloses a vacuum-packaging machine for packaging waste having a container space for receiving an open bag, as well as a hinged lid, which hermetically seals the container space to the outside, and a discharging device. So that the lid is not soiled on its inner side, the bag is provided with a collar and a groove connected thereto. The latter is suspended in fixing bolts in the lid.
CA1235648 discloses a method and apparatus for vacuum shrink packaging a product that includes the steps of placing the product in a heat shrinkable thermoplastic bag; then shrinking the bag in a heated gaseous medium, while partially constricting the mouth of the bag to cause ballooning of the bag, further provided that the constricting is selected such that shrinkage of the bag overcomes the ballooning to collapse the bag onto the product; and then placing the bag in a vacuum chamber followed by vacuumizing and in-chamber sealing, further provided that the rate of vacuumizing is limited to substantially prevent reballooning of the bag.
CA1235942 discloses a method and apparatus for vacuum packaging a molded meat product in a cook-in bag that includes the steps of vacuum stuffing a substantially deaerated moldable meat product into a thermoplastic bag lining a cooking mold, the bag having a length greater than the mold to define a bag neck; substantially removing any meat from the bag neck; and then, while still under vacuum, gathering and clipping the bag neck.
U.S. Pat. No. 6,343,537 discloses a dual stroke cylinder having a piston for sliding in a cylinder, a rod of the piston, and a sleeve fitted over the rod and passing through a rod hole of the cylinder. A lock portion is provided to an outer periphery of a tip end portion of the rod. The sleeve having an outer peripheral face for sliding in the rod hole in the cylinder and an inner peripheral face for sliding on an outer peripheral face of the rod is provided with an engaging portion on an inner end side to be engaged with an inside of the rod hole of the cylinder and an engaging portion at an outer end side to be engaged with the lock portion of the rod.
EP2174538 discloses a working device for an agricultural vehicle a working unit having a work organ, where an adjustment device is subjected with a pressure for adjusting the working unit between a working position and a transport position. The adjustment device has a piston of an adjuster that is adjustable along a piston rod.
EP0914896, DE3809461, DE102009037959, and U.S. Pat. No. 3,469,503 disclose devices having double cylinders in which a piston head is movably arranged within a cylinder, wherein the cylinder is movably arranged with another cylinder.
It is an object of the invention to provide a packaging apparatus provided with a two-stroke actuator that facilitates efficient and reliable movement of a vacuum chamber relative to a table during operation of a packaging apparatus.
It is a further object of the invention to provide a method of operating a packaging apparatus provided with two-stroke actuators in accordance with the present invention.